This document discusses the transport layer of the OSI model and protocols TCP and UDP. It aims to explain the role of transport layer protocols in supporting reliable and unreliable communications across networks. TCP provides reliable, connection-oriented communications using mechanisms like port numbers, sequencing, acknowledgments and retransmissions to ensure reliable data delivery. UDP provides simpler, connectionless delivery of datagrams and is best suited for real-time delivery when reliability is less important. The document will analyze how these protocols operate and manage sessions and data transmission.